Hope everyone had a good Christmas and new yrs, unfortunately I'm bringing a problem that plagued me from last year into this. I built a little jig for testing energy from small piezo igniters. It cycles them several thousand times and records the data. The basic system is I'm wanting to record the energy levels in the piezo device and see how it falls off over time. However much above 250uJ from the piezo and the LCD will crap itself either going blank, missing a line, moving half a line up etc. The Piezo discharges itself through a schottky bridge rectifier into a cap, then I just measure the voltage on the cap with the ADC through a 10K resistor. It works fine until I get a piezo thats a little gruntier than the rest and that will just wipe out my LCD until power down and back up again. The power to the LCD is filtered through a resistor and a bunch of caps I think a couple of 33pF, 1nF, 100nF, 1uF and 47uF. But it seems to make little if any difference.

One thing thats interesting is the screen will still go blank if there is no positive from the cap hooked up, hows the best way to quench out any nasties coming through the line? Ferrite beads? Small inductors?

For the moment it has me beat, any thoughts would be greatly appreciated.

Many thanks